Convertible seat bed units of various constructions and useable both for seating and sleeping are well known in the art. In many of these, a flexible bed platform is held in a curved condition in a sofa portion of the seat bed unit. Once the seat cushions are removed, the bed platform can be pulled out of the sofa portion and is straightened out. Convertible sofa-bed units are also known in which a rigid seat support frame is mounted on a main frame for movement of the seat between a rearward seating position—in which a rear edge of the seat is located under a back rest—and a forward sleeping position, in which the rear edge of the seat is located forwardly of the backrest and is raised to level the bed. A typical patent disclosing such an embodiment is the Quakenbush U.S. Pat. No. 3,816,860 patent. Another such sofa-bed unit is disclosed in the Fox U.S. Pat. No. 3,005,997 patent. A convertible sofa-bed unit utilizing a flexible support frame that may be extended from, or retracted into, the unit is disclosed by Singer in U.S. Pat. No. 4,586,206. Although satisfactory in most respects, these sofa-beds are primarily for sleeping and are unsuitable as furniture seating units.
In U.S. Pat. No. 4,166,299 for an extendable bed mechanism, DuShane et al. describe an extendable bed that may be placed in either a fully extended position or in a fully retracted position. Although satisfactory for a sleeping unit, the extendable bed mechanism of DuShane et al. would be entirely unsatisfactory for use as a seating unit. First, DuShane et al.'s system does not enable the bed or support structure to be secured at an intermediate position, that is between a fully retracted position and a fully extended position. Second, DuShane et al. utilize a first movable bed panel that is pulled across the top of a second panel. The resulting minimal distance between these panels would not allow the incorporation of cushioning provisions between the panels, such as coil springs, expanded metal devices, S springs, or fabric supports. Third, it is doubtful that the mechanism of DuShane et al. would properly operate or at least smoothly, if one or two persons remained laying on the bed while attempting to extend the bed outward. Accordingly, there is a need for a mechanism, particularly one adapted for use in a seating unit, that allows a seat or other support structure to be placed in any one of numerous positions between a fully retracted and a fully extended position. It would also be desirable that such a movable support panel accommodate cushioning provisions under the support panel. And, as will be appreciated, the movable support panel and its related assembly should operate smoothly as the support panel is moved from one position to another, particularly when supporting the weight of one or more persons.
Another problem with conventional couches and seats is that the extension of the seat frame in relation to the main frame cannot be controlled so that the seat frame can be locked in relation to the main frame at a number of positions between a fully retracted position and a fully extended position. Rather, in the sofa-bed units disclosed in the Quakenbush '860 patent and the Fox '997 patent, there is only a fully retracted position and a fully extended position. This is understandable since the thrust of these patents is to a sofa which converts into a bed rather than a sofa having a slidable seat section. The sofa-bed unit disclosed by Singer in the '206 patent is positionable only between a “bed” (extended) position and a “sofa” (retracted) position. The extendable bed mechanism disclosed by DuShane, et al. is similar in that it only provides a fully retracted position and a fully extended position.
In addition, the known sofa-bed units do not allow a sliding motion of the seat frame in relation to the main frame when a person is seated on the seat frame. Rather, the person has to get up to move the seat frame. This is understandable because the seat frame is being turned into a bed. The mechanism of DuShane, et al. exhibits a similar difficulty.
It would be desirable to have a seat frame that can be moved while the person remains seated and that can be locked into a number of positions between a fully retracted position and a fully extended position so that the person can regulate the length of the seat portion.
Accordingly, it has been considered desirable to develop a new and improved seating system which can be used on couches, sofas, love seats or chairs which would overcome the foregoing difficulties and others, meet the above stated needs and provide better and more advantageous overall results.